Brake systems of modern motor vehicles are often equipped with pneumatic brake boosters. Such brake systems require, for the satisfactory generation of braking force, a vacuum which in many cases has to be made available by means of dedicated pump assemblies. Because continuous availability of a braking force which is sufficient at any time is safety-relevant to a high degree, particularly stringent requirements are made of the vacuum supply in terms of its reliability, which requires continuous monitoring of the vacuum level which is available for the brake booster.
Brake systems with pneumatic differential-pressure-controlled brake boosters are known from motor vehicles, which brake systems have electromotively-driven pump assemblies with expeller elements which can be moved in a stroke-like fashion in order to supply vacuum to the brake booster at least in a supportive fashion, and in which brake systems the vacuum level is measured by means of pressure sensors which are embodied in a redundant fashion. The function monitoring of the brake system and control of the pump assembly therefore depend on the signals of the pressure sensors. In order to increase the reliability of the measurement and to diagnose pressure sensor errors in good time, the values which are recorded simultaneously by means of two pressure sensors are compared with one another and in this way noticeable implausible signals of one of the sensors are detected.
An intensive outlay in terms of costs and installation space owing to the use of two pressure sensors with associated connections and lines as well as necessary evaluation hardware and control hardware is considered to be in need of overall improvement.